Treatment of lignite and the like.



T. RIGBY.

TREATMENT OF LIGNITE AND THE LIKE.

APPLICATION FILED JAN: 11, 1913.

1,21 9, 1 55 Patented Mar. 13, 1917.

2 SHEETS-SHEET I.

WITNESSES Tho lNvsgTogl Wfim BY 7m ATTORNEY v T. RIGBY.

TREATMENT OF LIGNITE AND THE LIKE.

1,21 9,155 APPLICATION FILED JAN. H, 1913- Patented Mar 2 SHEETS-SHEET 2.

R wm on ms 0 m 0 In I B ATTORNEY version into briquet fuel.

THOMAS RIGIBY, OF DUMFRIES, SCOTLAND, ASSIGNOR 0F ONE-HAL}? T0 NILS TE STRUP,

- OF LONDON, ENGLAND.

TREATMENT 0F LIGNITE AND THE LIKE.

Specification of Letters Patent. Patented Mar. 13, 1917.

Application filed January 11, 1913. Serial No. 741,583.

land, and residing at 61 Loreburn street,

Dumfries, Scotland, have invented certain new and useful Improvements in and Relating to the Treatment of Lignite and the like, of which the following is a specification.

This, invention relates to the treatment of lignite and the like and has for its object to provide an improved method for the treatment thereof applicable more particularly in the drying of the same preparatory to com In the conversion of li ite into briquet fuel it is customary to suppdz y the same to Schulze or other driers and to dry the same down to a relatively small water content after which it is supplied to the briqueting'presses.

,Thepresent invention consists broadly in effecting removal of moisture from lignite or the like by pulverizing the material and introducing it into a stream of hot products of combustion by which it is dried to a certain extent and conveyed to the desired lo-.

cality such as to Schulze driers in which the material is then further dried.

The accompanying diagrammatic draw ings'show two forms of apparatus by which the invention may be'carried into effect;

In Figure 1, t is a conveyer band conducting moist lignite to a disintegrator b from which the material passes into a mill 0, through a shaking sieve d and into a distributing device 6 by which the powdered material is introduced in regular quantities into a rapidly flowing stream of hot waste products of combustion passing throughthe flue 7 from the boiler furnace a of the 1nstallation of which the briqueting plant forms part. The material is carried with. this stream of gases, passes the fan 9 and enters the vertical flue h the valve u of which is under these circumstances closed. The

vices 7', the separated powder entering the hopper le of asteam heated Schulze drier Z comprising a rotating shell occupyingan inclined position and containing a number of tubes through which the material gradually passes from one end to the other during the rotation lof the apparatus while it is heated .by steam admitted to the space between the tubes and the casing and the gases then passing by the flue m, provided with the branch n, to the exit end of the Schulze drier where the more completely dried powder is once more and after passing through a double clapper device (not shown) by a distributing device 4) introduced into the stream of gases and carried thereby through the duct sto the second series of separators 0 above the bunker p which is in connection with the briqueting press 20. The gases noW leave by the duct 9 and together with the exit gases from the drier enter the tower 1' wherein the gases are scrubbed to recover the residual dust not separated by the cyclones.

It is to be understood that in order to obtain' flue gases at a suitable temperature'it is necessary to burn an excess of fuel in the furnace at but this is beneficial as increasing the heat transmission and therefore evapo-' rative capacity without corresponding heat loss in the system. A small quantity of the gases in the flue m, which still contain say' 4% of dust and are under pressure, is passed As the hottest gases meet, at the distributer e, the wettest' material andcontain, as

contact with the material throughout is such" as to insure safety from ignition or exploslon.

In practice it has been observed that if the temperature ofthe gases in the duct be main-- tained at above dew .point and if their velocity exceed about 50 feet per second there is no tendency to stoppage in the ducts. It is preferable to keep up a very sl ght pressure in the duct.

If it is desired to avoid conveying the dried dust in a current of gases as above described, the above installation'may be modified as shown in Fig. 2, the installation shown in this fi re differing only from that already show in that a screw conveyer through the pipen to replace the air usually "passed through the drier-s.

w in a closed duct replaces the duct 8 and separators 0, the duct m being in this case directly connected to the scrubbing tower r. In this case the gases entering 'r from m tend to pass downward and fill all the spaces with inert gases but special provision may he easily made for passing inertgases into the con 'veyer and avoiding any possibility of ignition. 4 N

The drying effected by the flue gases can be varied by varying the length of the duct between the point of introduction and separation of the powder.

Where the drying gases are, as described above, obtained from a boiler furnace or from some other source from which the temperature may vary considerably the effect of such variations may be reduced by providing in the flue or duct 7 a mass of iron so that it may take up a considerable quantity of heat and act as thermal storage; Although other material than iron, such as brickwork, can be employed the former is preferable as more rapid in taking up and giving out heat.

By adopting the method above described economy of fuel and plant is effected while the direct'contact of the drying medium and the material to be dried favors in that step rapid and eificient heat transmission. The fact that by such a process the dust reaching the drier can be caused to contain 49% or less of moisture as against a water contentpf 55% or thereabout according to present practice, insures as stated a material saving in steam consumption and allows of reducing if desired, the size of the plant (driers and boilers), or on the other hand, of increasing its output and, again, allows of reducing the cost of new installations.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is 1. A method of drying inflammable solids such as lignite consisting in pulverizing the solid and then causing the resulting powder to be suspended in waste products of combustion until dried to the desired extent.

2. A method of drying lignite consisting medium, the method of drying powdered lignite consisting in dispersing it in a current of hot flue gases moving at a velocity of about 50 feet per second or over until dried to the desired extent.

4. A method of drying lignite consisting in reducing the lignite to a homogeneous powder, causing said powder to float in a, current'of hot products of combustion, separating the powder from said products and further drying the powder out of the contact with a drying medium.

5. A method of drying lignite consisting in reducing the lignite to a homogeneous powder, causing said powder to float in a current of hot products of combustion, separating the powder from said products and utilizlng the separated products of combustion to convey dried powder to be consolidated.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

' THOMAS RIGBY.

Witnesses:

EUTNAM H. MATTHEWS, JAMES HENDERSON. 

